The present invention relates to a technique of removing a lead-free solder from a slider pad in a magnetic disk drive and more particularly to a technique of removing a lead-free solder from a slider pad in such a mode as is suitable for re-utilization of a head/slider.
In a magnetic disk drive, a head formed on a slider (an integral structure of the head and the slider will hereinafter be referred to as “head/slider”) flies while retaining a slight gap from a surface of a magnetic disk and writes or reads data to or from the magnetic disk. An air bearing surface (“ABS” hereinafter) is formed on a surface of the head/slider opposed to the magnetic disk. The ABS is formed so that a positive pressure as a lifting force is generated in the slider when an air flow created on a surface of a rotating magnetic disk passes between the ABS and the surface of the magnetic disk. As the case may be, the ABS is formed so as to also generate a negative pressure for stabilizing posture when the head/slider flies. The head/slider is attached to a spring structure called flexure. While the head/slider flies over the surface of the magnetic disk, the head/slider performs pivotal motions or gimbaled motions so that the spacing between the head and a magnetic layer of the magnetic disk is within a predetermined range.
The flexure is secured to a load beam, which in turn is secured to an actuator assembly, the actuator assembly being driven by a voice coil motor (“VCM” hereinafter). In the magnetic disk drive there is provided a circuit board on which are mounted circuit components for data communication and for controlling the magnetic disk drive. The circuit board and the head are electrically connected with each other through a lead wire. A slider pad connected to the head is formed on an end face of the head/slider. The slider pad and a lead pad formed on an end portion of the lead wire disposed near the slider/pad are soldered to each other.
In a magnetic disk drive manufacturing process, there sometimes occurs a case where a defect is found on the lead wire side in an electric test conducted in an integrated state of the lead wire and the head after the connection of the slider pad with the lead pad. In a wiring integrated suspension wherein a wiring layer as a lead wire is integral with a metal layer of a flexure, it is difficult to repair the lead wire. Further, since the cost of the head/slider is high, the head/slider is re-utilized if there is found no defect therein. For re-utilizing the head/slider it is necessary to remove the soldered connection between the slider pad and the lead pad and remove the head/slider from the flexure.
The conventional tin-lead eutectic alloy solder is relatively soft even at room temperature, so even if it is scraped off from the slider pad with use of a cutting tool at room temperature, there is no fear of damage to the slider pad and the head/slider can be re-utilized. Recently, for the prevention of environmental pollution, a lead-free solder has come to be used in many electric devices. The lead-free solder when solidified is harder than such a lead-containing solder as tin-lead eutectic alloy solder and therefore, when an attempt is made to scrape off the lead-free solder from the slider pad with use of a cutting tool at room temperature, there arises the problem that the slider pad is damaged and it is virtually impossible to re-utilize the head/slider.
Patent Document 1 (Japanese Patent Laid Open No. Hei 7-106739) discloses a technique of heating a packaging substrate to a temperature of not higher than the melting point of solder by means of a heater to decrease the peeling strength of a solder ball relative to flux, followed by contact of an adhesive layer in a suction device with the packaging substrate, and peeling the solder ball from the packaging substrate with an adhesive force. Patent Document 2 (Japanese Patent Laid Open No. Hei 5-152727) discloses a technique of heating a printed wiring board to a predetermined temperature higher than the softening temperature of flux and lower than the melting temperature of solder, rubbing a surface of the printed wiring board with a brush and at the same time sucking air in the rubbed packaging surface area to peel and absorb a solder ball adhered to the packaging surface. Patent Document 3 (Japanese Patent Laid Open No. Hei 1-130590) discloses a technique of softening flux with heated steam and removing the flux and a solder ball with a blowing force. Patent Document 4 (Japanese Patent Laid Open No. Hei 11-26918) discloses a technique of heating solder to a softening temperature thereof and scraping off the solder with a scraping edge.